Push button type electric switches are well known as illustrated by U.S. Pat. No. 4,385,214 issued May 24, 1983, and assigned to the assignee of the present invention. While the push button structure disclosed in the '214 patent includes an interlock mechanism that provides a commercially acceptable operation, it is deficient in that it does not include a mechanism which will indicate the sequential operating steps as the switch plunger is depressed. Another switch that enjoys commercial acceptance is disclosed in a U.S. application for Pat. Ser. No. 292,776 filed August 14, 1981, now U.S. Pat. No. 4,388,503 and assigned to the assignee of the present invention. A deficiency in the switch when made according to the '776 patent application is that the switch does not include an interlock function to prevent simultaneous energization of electrical loads controlled by the switch.
The present invention has general applicability and is most advantageously applied to push button switches. One type of installation to which the present invention relates is an installation using a multiple speed reversible electric motor wherein it is required that the switch have a positive interlock to prevent simultaneous energization of the forward and reverse motor operation and positively and tactilely indicate the various discrete speed operating steps of the motor.